attempt_context Class Reference

The attempt_context is used for all synchronous transaction operations. More...

#include <couchbase/transactions/attempt_context.hxx>

Public Member Functions
virtual auto	get (const couchbase::collection &coll, const std::string &id) -> std::pair< error, transaction_get_result >=0
	Get a document from a collection.
virtual auto	get_replica_from_preferred_server_group (const couchbase::collection &coll, const std::string &id) -> std::pair< error, transaction_get_result >=0
	Get a document copy from the selected server group.
template<typename Transcoder = codec::default_json_transcoder, typename Document , std::enable_if_t<!std::is_same_v< codec::encoded_value, Document >, bool > = true>
auto	insert (const couchbase::collection &coll, const std::string &id, const Document &content) -> std::pair< error, transaction_get_result >
	Insert a document into a collection.
template<typename Transcoder = codec::default_json_transcoder, typename Document , std::enable_if_t<!std::is_same_v< codec::encoded_value, Document >, bool > = true>
auto	replace (const transaction_get_result &doc, const Document &content) -> std::pair< error, transaction_get_result >
	Replace the contents of a document in a collection.
virtual auto	remove (const transaction_get_result &doc) -> error=0
	Remove a document.
auto	query (const std::string &statement, const transaction_query_options &options={}) -> std::pair< error, transaction_query_result >
	Perform an unscoped query.
auto	query (const scope &scope, const std::string &statement, const transaction_query_options &opts={}) -> std::pair< error, transaction_query_result >
	Perform a scoped query.
virtual	~attempt_context ()=default

Detailed Description

The attempt_context is used for all synchronous transaction operations.

In the example below, we get a document then replace its content:

    auto [tx_err, tx_res] = cluster.transactions()->run(
      // [3.1] closure argument to run() method encapsulates logic, that has to be run in
      // transaction
      [=](std::shared_ptr<couchbase::transactions::attempt_context> ctx) -> couchbase::error {
        // [3.2] get document
        auto [err_ctx, doc] = ctx->get(collection, id_1);
        if (err_ctx.ec()) {
          fmt::print(stderr, "failed to get document \"{}\": {}\n", id_1, err_ctx.ec().message());
          // [3.3] don't continue the transaction logic
          return {};
        }
        // [3.4] replace document's content
        ctx->replace(doc, tao::json::value{ { "some", "other content" } });
        return {};
      });
    // [3.5] check the overall status of the transaction
    if (tx_err.ec()) {
      fmt::print(stderr,
                 "error in transaction {}, cause: {}\n",
                 tx_err.ec().message(),
                 tx_err.cause().has_value() ? tx_err.cause().value().ec().message() : "");
      retval = 1;
    } else {
      fmt::print("transaction {} completed successfully\n", tx_res.transaction_id);
    }

Constructor & Destructor Documentation

~attempt_context()

virtual ~attempt_context ( )

virtualdefault

Member Function Documentation

get()

virtual auto get ( const couchbase::collection & coll, const std::string & id ) -> std::pair< error, transaction_get_result >

pure virtual

Get a document from a collection.

Fetch the document contents, in the form of a transaction_get_result. This can be used in subsequent calls to attempt_context::replace or attempt_context::remove

Parameters

coll	The collection which contains the document.
id	The unique id of the document.

Returns

The result of the operation, which is an error and a transaction_get_result.

get_replica_from_preferred_server_group()

virtual auto get_replica_from_preferred_server_group ( const couchbase::collection & coll, const std::string & id ) -> std::pair< error, transaction_get_result >

pure virtual

Get a document copy from the selected server group.

Fetch the document contents, in the form of a transaction_get_result. It might be either replica or active copy of the document. One of the use cases for this method is to save on network costs by deploying SDK in the same availability zone as corresponding server group of the nodes.

Parameters

coll	The collection which contains the document.
id	The unique id of the document.

Returns

The result of the operation, which is an error and a transaction_get_result.

See also

network_options::preferred_server_group

https://docs.couchbase.com/server/current/manage/manage-groups/manage-groups.html

insert()

template<typename Transcoder = codec::default_json_transcoder, typename Document , std::enable_if_t<!std::is_same_v< codec::encoded_value, Document >, bool > = true>

auto insert ( const couchbase::collection & coll, const std::string & id, const Document & content ) -> std::pair<error, transaction_get_result>

inline

Insert a document into a collection.

Given an id and the content, this inserts a new document into a collection. Note that currently this content can be either a <std::vector<std::byte>> or an object which can be serialized with the codec::tao_json_serializer.

Template Parameters

Document

Type of the contents of the document.

Parameters

coll	Collection in which to insert document.
id	The unique id of the document.
content	The content of the document.

Returns

The result of the operation, which is an error and a transaction_get_result.

query() [1/2]

auto query	(	const scope &	scope,
		const std::string &	statement,
		const transaction_query_options &	opts = {} ) -> std::pair< error, transaction_query_result >

Perform a scoped query.

Parameters

scope	Scope for the query.
statement	The query statement.
opts	Options for the query.

Returns

The result of the operation, with is an error and a transaction_query_result.

query() [2/2]

auto query	(	const std::string &	statement,
		const transaction_query_options &	options = {} ) -> std::pair< error, transaction_query_result >

Perform an unscoped query.

Parameters

statement	The query statement.
options	Options for the query.

Returns

The result of the operation, with is an error and a transaction_query_result.

remove()

virtual auto remove ( const transaction_get_result & doc ) -> error

pure virtual

Remove a document.

Removes a document from a collection, where the document was gotten from a previous call to attempt_context::get

Parameters

doc	The document to remove.

Returns

The result of the operation.

replace()

template<typename Transcoder = codec::default_json_transcoder, typename Document , std::enable_if_t<!std::is_same_v< codec::encoded_value, Document >, bool > = true>

auto replace ( const transaction_get_result & doc, const Document & content ) -> std::pair<error, transaction_get_result>

inline

Replace the contents of a document in a collection.

Replaces the contents of an existing document. Note that currently this content can be either a <std::vector<std::byte>> or an object which can be serialized with the codec::tao_json_serializer.

Template Parameters

Content

Type of the contents of the document.

Parameters

doc	Document whose content will be replaced. This is gotten from a call to attempt_context::get
content	New content of the document.

Returns

The result of the operation, which is an error and a transaction_get_result.

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The documentation for this class was generated from the following file:

• couchbase/transactions/attempt_context.hxx